The present invention relates to a wire harness joint for connecting harness within a vehicle such as motorcar and, particularly, to such a wire harness joint which can be reduced in thickness, disposed within the vehicle at any position and yet assembled in an easy and simple manner.
For example, as shown in FIG. 12, an electric circuit used in the vehicle such as motorcar comprises a battery 101, two trunk wires 111 connected to the battery 101 and branch wires 112 connected in parallel between the trunk wires 111. Each of the branch wires 112 may include a switch 103, an electric lamp 104, a motor 105 or the like. A joint 106 may be used to connect between the trunk and branch wires 111, 112. Such a joint may include a splice terminal, a joint connector, a welded joint and others.
As can be seen from FIG. 13, the splice terminal comprises a terminal 114 clamped over the bundled ends of the naked and exposed conductors 110a of the trunk and branch wires 111, 112 to be joined and a plastic tape or tube 113 covering the terminal 114 and naked conductors 110a to provide an insulation. Such a splice terminal has an advantage in that it can provide a compact and simple branch at any position.
However, this operation in which the trunk and branch wires 111, 112 are naked to expose the conductors 110a and then the terminal 114 is clamped over the bundle of the exposed conductors 110a is troublesome and difficult to be automated. Furthermore, the covering of the joint section with the plastic tape 113 or the like must manually be performed. This raises a problem in that the insulating property is not made stable.
In place of the splice terminal, therefore, the joint connector or welded joint has been broadly used in the art. As can be seen from FIG. 14, the joint connector comprises female terminals 120 attached to the conductors 110a of branch wires 112, a comb-like bus bar 121 fitted into the female terminals 120 and a connector housing 122 covering the female terminals 120 and bus bar 121. Such a joint connector raises another problem in that it has an increased number of parts and is increased in manufacturing cost.
On the other hand, as shown in FIG. 15, the welded joint is formed by welding the exposed conductors 110a of wires 110, turning the welded conductor portions, covering the turned conductor portions with an insulation cap 123 and winding a plastic tape 113 around the turned conductors. The welded portions of the conductors 110a must be turned in view of the structural and operational constraints. However, the turned conductor portions form a thicker bundle of wires which cannot optionally be mounted at any desired position.
All of the splice terminal, joint connector and welded joint structures raise a further problem in that they are constrained in number of joinable circuits, in addition to the aforementioned problems.
In order to deal with the increased number of circuits, the provision of a plurality of joint boxes for integrating a plurality of dispersed joints has been considered. FIG. 16 shows such a joint box which comprises an upper casing 131, a lower casing 132 mounted on the upper casing 131 to form a space therewith, a multi-layer bus bar 133 located within the space between the upper and lower casings 131, 132 and an insulation plastic plate 134 located between the layers of the multi-layer bus bar 133, the bent tips of the bus bar 133 forming male terminals 133a which outwardly protrude from between the upper and lower casings 131, 132. These male terminals 133a are connected to the respective female terminals on the ends of wires in a wire harness (not shown). The bus bar 133 is pressed and stamped from a flat conductive sheet which may be made of copper, copper alloy or the like. In FIG. 16, reference numeral 150 denotes a housing on the upper casing; and 151 through-holes formed in the insulation plate to receive the male terminals 133a. 
Recently, in place of such a combination of the bus bar 133 with the insulation plate 134, a flexible printed board (FPC) may be utilized for the same purpose. FPC is connected to tangs on the tip of a wire harness, but not have the male terminals 133a. 
A further wire harness joint constructed according to the prior art will now be described with reference to FIG. 17. The wire harness joint comprises wiring circuit assemblies 10 which are formed by wire harnesses and insulation films applied to a plurality of flexible linear and flat cables (FFC""s) 11 on one or both sides in the middles or extremities of the wire harnesses 30. Three transverse wiring circuit assemblies 10 are superposed on the longitudinal wiring circuit assembly 10. Connection holes 23 are formed through the insulation films at the portions of the superposed FFC""s 11 to be connected.
However, such a technique also raises the following problem:
Since the joint box is weight and bulk, a number of such joint boxes cannot be located within the motorcar at any desired positions. It is undesirably usual that the joint boxes are mainly located within the engine room and/or on the back of the firewalls. Such a constraint increases the length of wires in the wire harnesses placed within the engine room or the like.
Since the male terminals 133a on the tips of the wire harness must be formed by turning the tips of the bus bar 133, the operation required thereby is troublesome. Furthermore, the bus bar 133 has its increased thickness, for example, equal to 0.65 mm or 0.8 mm, for the standards of tab thickness in the male terminals 133a. 
Consequently, the prior art bus bar 133 cannot be used to increase the compactness of circuit, resulting in increase of the joint box dimensions. Since an increased number of joint boxes cannot be placed within the engine room to increase the number of electric parts, the prior art cannot meet a need of improving the comfortability in the passenger motorcar.
In the wire harness connecting to the male terminals 133a of the joint box, the wires are colored while the tips are arranged in alignment with the pitch in the male terminals 133a of the bus bar 133 using the connector housing, the female terminals being then clamped against these tips. Such an operation is troublesome and raises a further problem in that the cost required to machine and work the parts including the female terminals and housing will increase.
Since FFC""s 11 are parallel and linear in the wire harness joint structure of the prior art, it can inexpensively be produced in a continuous manner, but the superposing and assembling operations becomes troublesome. Thus, the prior art can only produce such a wire harness joint which the FFC""s 11 of the wire harness 30 are parallel and linear with a reduced number of circuits.
It is therefore an object of the present invention to provide a wire harness joint which can be reduced in thickness, disposed within a motorcar at any position and yet inexpensively assembled in an easy and simple manner.
In one aspect of the present invention, it provides a wire harness joint comprising a wiring circuit assembly for connecting wire harnesses which a plurality of flexible flat cables are arranged in parallel, and insulation film applied to said wiring circuit assembly on one or both sides, said wiring circuit assembly having a plurality of flexible flat cables with connections for connecting said wire harnesses, said plurality of flexible being arranged separately from one another so that said flexible flat cables will not intersect one another, and said insulation film having windows formed therethrough at positions corresponding to said connections.
In the second aspect of the present invention, it provides a wire harness joint comprising a wiring circuit assembly for connecting wire harnesses which a plurality of flexible flat cables are arranged in parallel, and insulation film applied to said wiring circuit assembly on one or both sides, said wiring circuit assembly having a plurality of flexible flat cables with connections for connecting said wire harnesses, said plurality of flexible being superposed one over another into plural layers with said insulation film therebetween, and said insulation film including windows formed therethrough at positions corresponding to said connections
In the third aspect of the present invention, it provides a wire harness joint comprising a wiring circuit assembly for connecting wire harnesses which a plurality of flexible flat cables are arranged in parallel, and insulation film applied to said wiring circuit assembly on one or both sides, said wiring circuit assembly including a plurality of openings formed therethrough and a connection formed near each of said openings for connecting one of said wire harnesses, and said insulation film including windows formed therethrough at positions corresponding to said connections.
The wire harness joint includes connection terminals each of which has a flat face and a plurality of upstanding legs formed on the opposite side edges of said flat face. The tips of said upstanding legs opposed to each other are turned toward each other so that they will penetrate the top face of said wiring circuit assembly from the bottom face of the same to provide an electrical connection between each of said connection terminals and said wiring circuit assembly.
The wiring circuit assembly, insulation film and connection portions of said wire harness connected are covered with an adhesive insulation film. The whole or part of the adhesive insulation film is fixedly mounted on any structural material in the vehicle or instrument.
The wiring circuit assembly, insulation film and connection portions of said wire harness connected are shaped for the configuration of the mount portion of the vehicle or instrument. The whole or part of the shaped portion is fixedly mounted on the structural material of the vehicle or instrument.
The wiring circuit assembly is folded to align the extremities of said connections. In such a case, the wiring circuit assembly may be partially cut or be formed with slits.
Therefore, the wire harness joint of the present invention can be reduced in thickness so that it can be mounted in any desired structure at any position and can easily and simply be assembled.